hadfield and a



R. A. HADFIELD AND A. G. M. JACK.

CAPPED ARMOR PIERCING PROJECTILE AND CAP THEREFOR.

APPLICATION FILED APR. 23. I914. RENEWED MAR- 30, ISIT. 1,310,076.

Patented July 15, 1919.

2 $HEETSSHEET I- wine-S865:

ma COLUMBIA P R. A. HADFIELD AND A. G. M. JACK.

CAPPED ARMOR PIEBCING PHOJECTILE AND CAP THEREFOR.

APPLIJATION FILED APR. 23. 914. RENEWED MAB. 30.1911.

1 ,31 0,076. Patented July 15, 1919.

2 SHEETS-SHEET 2- wwy 'I'HL LOLLZMIUA mxmnusuum 50.. WASHINGTON, n. c

UNITED STATES PATENT OFFICE.

ROBERT ABBOTT HADFIELD, OF WESTMINSTER, AND ALEXANDER GEORGE MACKENZIE JACK, 0F SHEFFIELD, ENGLAND.

CAPPED ARMOR-PIERCING PROJEGTILE AND CAP THEREFOR.

Application filed April 23, 1914, Serial No. 883,873. Renewed March 30, 1917.

To all whom it may concern Be it known that We, Sir ROBERT ABBOTT HADFIELD, knight, F. R. S., and ALEXANDER GEORGE MACKENZIE JAoK, subjects of the King of Great Britain and Ireland, residing respectively, at Westminster England, and Sheflield, in the county of fork, England, have invented Improvements in or Relating to Capped Armor-Piercin Projectiles and Caps Therefor, of which t e following is a specification.

This invention has for object to provide caps for armor piercing projectiles that will enable projectiles fitted therewith to com pletely perforate hard faced armor plates in a more reliable and advantageous manner than heretofore usual both when striking normally and obliquely.

For this purpose according to the present invention a ca of the required weight is made of meta or alloy capable of'being stifl'ened or hardened and possessing considerable toughness or strength and subjected to a stiffening treatment such that the metal is caused to gradually increase in stiffness or hardness in a direction from the partthereof directly in front of the point of the projectile to the extreme front end or point of the cap as hereinafter described, the stifi'ness or hardness at the latter part of the cap approaching in some cases that of the hard face of the armor plate at which a projectile fitted with a cap is to be fired so that upon impact of the capped projectile against the plate the point of the projectile Wlll pass through cap material of gradually increasing stiffness or hardness and will reach and perforate the plate withoutbeing suddenly subjected to contact with a surface that is considerably harder than the front end portion of the cap material as has heretofore been usual. As a result, the point of the projectile is supported with a gradually increasing pressure from the moment of impact of the cap against the hard surface of the plate until it enters the plate, the sudden shock which the point of a projectile ordinarily receives when passing through the relatively soft metal of a cap and striking the hard surface of the plate being avoided with advantageous results.

A further result of using a cap of the kind referred to is that on impact against a hard faced armor plate, its stlflened or hardened front end point enters or bites into the hard Specification of Letters Patent.

Patented July 15, 1919.

Serial No. 158,731.

surface of the armor plate so as to center the capped projectile to some extent and effect an initial erforation, disintegration or fracture of sue 1 hard surface so as to relieve the hardened point of the projectile to some extent from this duty and. enable it and the remainder of the projectile to finish the work of perforating the plate and remain intact or unbroken or practically unbroken under adverse conditions and also at a lower velocity than would otherwise be possible.

In order to obtain the best results both for normal and inclined fire, not only should the cap be made of metal or alloy capable of being stiflened or hardened and possessing considerable toughness but it should be stiffened in such a manner that it should have a ball hardness at or near the middle or central portion or zone of the axial length of its front end portion of the order of about 350 to 500 on the Brinell ball scale, corres onding to a hardness of about 45 to as etermined b the scleroscope, the hardness decreasing rom this part rearwardly through what may be called a rearward ortion or zone, say to a ball hardness of a out 200 to 300, corresponding to say about 30 to 40 as determined by the scleroscope, near to or at a short distance in front of the point of the projectile and increasing from the said part in a forward direction through what may be called a forward portion or zone, say to a ball hardness of from 500 to 600, corresponding to from about 60 to 90 by the scleroscope, or even higher, at the extreme front end or point of the cap. Thus it will be understood that the major part of the front end portion of the cap by which is meant that portion that extends beyond a plane that is at right angles to the longitudinal axis of the cap and is at or ad j acent to the point of the projectile to which the cap is a plied, will be well below a ball hardness o about 600, that is to say a hardness which corresponds to glass scratchiiig hardness, the part having a ball hardness of from 350 up to say 560 being of gradually increasing stiffness While possessing great toughness while if the ball hardness of the extreme front end portion or point of the cap be increased up to 600 or above this ortion will be in the condition usually on erstood and technically known in connection with steel by the term hardened. In the latter case the front end ortion of the cap, as defined will have a sti cued forward portion surmounted by a hardened extreme front end portion or point the extent of which may be varied to suit requirement. If the hardness of the front end portion of the cap from the said central portion or ZOIlc increases in a forward direction to the extreme front end or point to a ball hardness terminating substantially below a ball hardness of 600. say to a limit not above 560 that is to say well below glass scratching hardness, then the front end portion of the cap will consist of a metal of gradually increasing hardness varying from a condition of softness and toug-ness up to a condition of toughness and stifiness but not to a condition correspondin to that understood by the term hardened. %n each case however the front end portion of the cap will be of sufficient stiffness and toughness as not to break up so quickly as a cap having a hardened front end ortion as heretofore proposed so that it wilFofler a more effective support to the point of the projectile upon impact against an armor late or other object, until such point reac 188 the object, than a cap the front end portion of which is hardened in the ordinary sense of the term.

The said cap may advantageously be made of nickel chromium steel containing a substantial amount of carbon, nickel and chromium to enable its front end portion to be stifi'ened to a suitably high degree and leave the rear end portion relatively soft and tough. For example, good results have been obtained with a cap made of nickel chromium steel of the following approximate composition, namely, carbon 34% (decimal three four per cent), nickel 3.86% (three decimal eight six per cent.) and chromium 1.78% (one decimal seven eight per cent). The percentages of carbon, nickel and chromium may however vary from those mentioned by way of example provided ,sirliicient carbon is present to enable the front end of t e cap to be stiffened or stiflen d and har'ened to the required degree. n some cases the carbon may amount to .6 to .7% (decimal six to decimal seven per cent).

In some cases the cap may be of Wrought iron or mild steel having a cemented front end portion.

The front end portion of the cap, which may be of conical or pointed shape, or of rounded or of other desired shape, is stiff sued to the required varying degrees by heating it to a suitable temperature and then quenching it in a. cooling medium. In the of 'a cap made of nickel chromium steel of the above mentioned composition, the front end portion of the cap may be heated say to a temperature of about 850 0., and then dipped to a suitable depth into water or other suitable quenching Inedium and allowed to remain there until it attains the desired stiffness, such as that hereinbefore mentioned, the stifl'ucss gradually decreasing toward the part thereof that will be adjacent to. the point of the projectile with which it is to be used, in such manner that the cap material in the neighborhood of the hard pointed front end portion of the projectile is soft and tough, or comparatively so.

For a cap suitable for a four and one eighth inch armor piercing projectile and having an axial thickness through its front end portion of about one inch, good results have been attained by heating the front end portion of the cap to a temperature of about 850" C. and stiffening the same in ordinary cold water to a depth of about half an inch; in the case of a cap having an axial thickness of about one and a half inches by stillening the front end portion of the cap to a depth of about five eighths of an inch and in the case of a cap having an axial thickness of about five eighths of an inch by stiffening the front end portion of the cap to a depth of about half an inch. By stiffening the cap in this way by dipping, it is found to have several zones of varying de grees of hardness, that is to say a front end zone having a ball hardness of 400 and upward, an adjacent rear zone having a decreasing ball hardness of from 400 to 300, and another and adjacent rear zone having a decreasing ball hardness of from about 300 to about 200 at or near the point of the projectile, the remainder or rear end portion of the cap having a ball hardness of about 200. The axial thicknesses through the front end portion of the caps mentioned above are given as examples only and can be increased or decreased to suit requirement and the caliber of the rojectiles with which the caps are to he used but not necessarily in direct proportion to the oalibers of. the projectile.

In the accompanying drawings Figures 1, 2 and 3 are sectional elevations showing capped projectiles embodying the present invention.

igs l and 2 show pro'ectiles a each fitted With a cap 6 of ogiva sha c with a conical or pointed front end ma e according to the present invention and having a front end portion the axial thickness of which can be made of different lengths as indicated by the dotted lines 5 ,1) and b the cap in Fig. 1 bein shown fittedto a projectile the ogival s aped head portion of which has a radius of curvature approximately equal to two calibersofthe projea tile while the cap in. Fig. Zis shown fitted to a projectile the head portion of which has a smaller radius of curvature.

In a cap constructed and st-ifl'e das descrlbed, the amount of material aving a ball hardness of 250 and over may constitute the whole or practically the whole portion of the cap in front of the point of the pro'ectile.

aps made as hereinbefore described may advantageously be subjected to a preliminary heat treatment before being subjected to the stiffening treatment proper. Thus, the'nickel chromium steel cap, in the rough forged shape, may be heated all over to about 800 to 850 0., then quenched all over-in oil, water or other suitable medium to a temperature of under 400 C., then reheated to about 740 C. and allowed to cool below 400 C. then reheated to about 600 C. and then finally quenched all over in water. The cap is then machined to the required shape after which its front end portion is heated say to about 850 C. and stifl'ened in the manner hereinbefore described.

When a cap according to the invention is made of wrought iron or soft steel with a cemented front end portion, the cementation process should be carried out in such a manner as to impregnate the greater part of the front end ortion of the ca with a suitable amount 0 carbon such as indicated in connection with the nickel chromium steel hereinbefore referred to. Such a cap may be stifiened or hardened in the manner hereinbefore described for the caps made of nickel chromium steel.

With the object of increasing the lateral support offered by the cap to the pointed end portion or nose of the projectile at the critical moment, namely when the point or nose reaches the armor plate and this without materially increasin the weight of the cap, the ogival or other s aped forward end portion of the cap may be provided intermediate of its front and rear parts with an external annular circumferential bead or ridge which may be of curved outline in cross section. Fig; 3-is a sectional elevation showing a projectile a fitted with an ogival shaped cap I) provided with a bead or extension at 0 such as referred to.

In modern armorpiercing projectiles designed for angle attack the weight of the cap usually forms a considerable proportion of the total weight of the capped projectile-it may be say about 15% thereofwith the result that the striking energy of the projectile itself, available for effecting perforation of an armor plate, after impact and dispersal of the cap, is thereby very considerably less than the total initial striking 'energy of the combined projectile and cap.

One of the objects of the present invention is therefore to provide a capped projectile that can perforate hard faced armor plate without becoming broken up, or broken up to such an extent asto seriously detract from its effective action, either when strikmgl the plate normall or obliquely under di 'cult conditions an wherein the weight of the cap relatively to the total weight of the capped projectile shall be smaller than usual so that for any iven weight of capped projectile the projecti e proper can be made of relatively greater weight and strength and will consequently possess, after impact and dispersion of the cap, greater energy and efficiency than usual, which shall be available for enabling it to better perforate the armor plate and yet remain in an intact or not seriously broken up condition.

To this end an armor piercing projectile is provided with a cap having a stiffened or hardened front end portion and a relatively soft rear portion in contact with the hard front end portion of the projectile as hereinbefore described and made of a weight of the order of from about five to twelve per cent. of the weight of the combined projectile and cap. In the case of an armor piercing projectile of about four and one eighth inches diameter, good results have been obtained with hardened caps such as hereinbefore described having weights varying from as low as twenty-three up to sixty ounces, constituting from about 4.5% to 12% of the weight of the combined projectile and cap.

Where necessary, a hollow point or air deflector of known kind may be applied over the front end portion of the cap so as to give the capped projectile the necessary contour but the use of such a hollow point or air deflector forms no part of the present invention.

What we claim is:-

1. An armor piercing projectile fitted with a cap having its front end portion made of gradually increasing stiffness, as distinguished from being hardened, in a forwardly extending direction from the part thereof in front of the point of the pro jectile.

2. An armor piercing projectile fitted with a cap made of nickel chromium steel and of gradually increasing stiffness, as distinguished from being hardened, in a forwardly extending direction from the part thereof in front-of a transverse plane passing through the cap near (the point of the projectile as set forth.

3. A cap for arm-or piercing projectiles having a hardened front portion gradually diminishing in hardness toward the rear, said cap having a hardness of from 350 to 500 ball hardness adjacent the center of the axial length of its front end portion, the hardness increasing therefrom forwardly to a hardness of from 500 to 600, and diminishing from said center rearwardly to a hardness of from about 300 to 200, substantially as described and shown.

4. A cap for an armor piercing projectile made of nickel chromium steel and of gradually increasing hardness from the rear toward the front end, the steel of said cap being low in carbon, having nickel above about three per cent. and chromium above about one per cent.

5. For an arm-or piercing projectile, a cap having its front end portion made of gradually increasing stiffness or hardness in a direction from the part thereof that will be in front of and near to the point of the projectile to which it is to be fitted and provided with an external annular circumferential head or extension, the diameter through said beaded portion being substantially less than the maximum diameter of the cap, substantial ly as described.

6. An armor piercing projectile fitted With a cap the front end portion of which is made of gradually increasin stifi'ness in a forward direction, as set orth, and the weight of which cap is of the order of from about four and a half to twelve per cent. of the weight of the combined projectile and g. An armor piercing projectile provided with a cap having its front portion gradually increasing in stiffness forward from the part adjacent the point of the projectile, and the extreme front end point or tip very hard, a preaching in hardness the hard face of t* e armor plate.

8. A cap for an armor piercing projectile having a relatively soft rear portion, a front portion gradually increasing in hardness toward the front end, and the extreme point or tip made very hard.

9. An armor piercing projectile provided with a cap having its front end portion of gradually increasing stiffness toward the front, said cap being made of nickel chromium steel or of wrought iron or mild steel, the extreme front point or tip having been hardened by ce'mentation before the remainder of the cap has been stiffened.

10. A cap for armor piercing projectile, having successive portions or zones of its front end portion, proceeding in a forward direction, of successively increasing degrees of ball hardness increasing from about 200 to 300 at the part of'the' cap adjacent to a transverse plane that would pass through the point of the projectile to which the cap is fitted.

11. A cap for an armor piercing projectile, the front portion of which is of gradually increasing hardness, but having its front end portion stiffened as distinguished from hardened and substantially below a ball hardness of the order of about 600.

12. A cap for an armor iercing reoctile the portion of which 1-, will o forward of the point of the projectile to which the cap is to be fitted is of gradually in creasing stiffness in a forward directiomthe final degree of stiflness adjacent the front not exceeding that corresponding to a ball hardness of about 560.

13. A cap for an armor piercing projectile having a hardened tip or nose carried by an unhardened but stiffened and toughened front portion.

14. A cap for an armor piercing projectile having its front portion made of gradually increasing stiffness, as distinguished from being hardened, in a forwardly extending direction and having a hardened extreme front tip or nose.

15. A cap for an armor piercing projectile, having a hardened front portion gradually diminishing in hardness toward the rear, said cap having a ball hardness of the order of about 360 adjacent to the center of the axial length of its front end portion, a ball hardness of the order of about 600 or above at the extreme tip and a ball hardness of the order of about 200 to 300 at the rear end of said front portion.

16. A steel cap for armor piercing projectiles containing a substantial amount of carbon, nickel and chromium, to enable its front portion to be stiffened and its rear portion relatively soft.

Signed at Sheffield this 15th day of January, 1914 and at Washington, D. (l, U. S. A., this 3rd day of February, r914.

ROBERT ABBOTT a rmail). ALEXANDER owner awrrrzm JicK.

Witnesses to the signature of Sir Robert Abbott Hadfield Anson- S. Tampa, ALFRED WmKmsoN. Witnesses to the signature of Alexander George Mackenzie Jack:

LUTHER J. (damn, E. MORTIMER;

Geples of this patent may be obtained for five cents each, by addressing the "flommialiomer ot imentl, Washington, D. 0." 

